Bartashevich Ekaterina V, Pendás Ángel Martín, Tsirelson Vladimir G
Department of Chemistry, South Ural State University (National Research University), 454080 Chelyabinsk, Russia.
Phys Chem Chem Phys. 2014 Aug 21;16(31):16780-9. doi: 10.1039/c4cp01257g.
The intramolecular interactions in substituted trinitromethanes, XC(NO2)3 (X = F, Cl, I, H) are studied and clarified by using a combination of the Quantum Theory of Atoms in Molecules (QTAIM), the non-covalent interaction analysis and the Interacting Quantum Atoms (IQA) methods. The stretching vibration modes are formed by the concerted displacements of atoms involved in the covalent bonds showing the significant multiatomic influence in substituted trinitromethanes. In agreement with that, the arrangement of the local reduced density gradient minima indicates that the electron density favors the non-covalent intramolecular interactions X···O and N···O. However, the corresponding QTAIM bond paths are not formed; instead, contacts, which we call uncompleted links in this context, are accompanied by "quasi-bonding channels" corresponding to the λ2() ≤ 0 regions on the sign[λ2(r)]ρ(r) contour maps. The intramolecular IQA energy contributions signal the appreciable electron exchange between the pairs of atoms associated with potential atomic interactions or the bond-path-free non-covalent links. The IQA analysis shows that the electrostatic term destabilizes FC(NO2)3 and distinctly stabilizes IC(NO2)3, whereas it is close to neutral in ClC(NO2)3. The exchange energy between the X atom and the NO2 groups, in contrast, stabilizes all the molecules.
通过结合分子中的原子量子理论（QTAIM）、非共价相互作用分析和相互作用量子原子（IQA）方法，对取代三硝基甲烷XC(NO₂)₃（X = F、Cl、I、H）中的分子内相互作用进行了研究和阐释。伸缩振动模式是由共价键中原子的协同位移形成的，这在取代三硝基甲烷中显示出显著的多原子影响。与此一致的是，局部约化密度梯度最小值的排列表明电子密度有利于非共价分子内相互作用X···O和N···O。然而，相应的QTAIM键径并未形成；相反，在这种情况下我们称之为未完成连接的接触，伴随着与sign[λ₂(r)]ρ(r)等高线图上λ₂( )≤0区域相对应的“准键合通道”。分子内IQA能量贡献表明，与潜在原子相互作用或无键径非共价连接相关的原子对之间存在明显的电子交换。IQA分析表明，静电项使FC(NO₂)₃不稳定，而使IC(NO₂)₃明显稳定，而在ClC(NO₂)₃中它接近中性。相比之下，X原子与NO₂基团之间的交换能使所有分子都稳定。
